LeftJoin with Multiple Conditions

Within MySQL I can do this LEFT JOIN:

LEFT JOIN table2 ON table1.myfield= table2.myfield AND table1.otherfield = table1.otherfield

Within Datatable Editor I can do this:

->leftJoin( 'table2', 'table1.myfield', '=', 'table2.myfield' )

My question is, how do I add a AND to the leftJoin?